log -L: improve error message on malformed argument

The old message did not mention the :regex:file form.

To avoid overly long lines, split the message into two lines (in case
item->string is long, it will be the only part truncated in a narrow
terminal).

Signed-off-by: Matthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

line-log.c

@@ -575,7 +575,7 @@ parse_lines(struct commit *commit, const char *prefix, struct string_list *args)
 
 		name_part = skip_range_arg(item->string);
 		if (!name_part || *name_part != ':' || !name_part[1])
-			die("-L argument '%s' not of the form start,end:file",
+			die("-L argument not 'start,end:file' or ':funcname:file': %s",
 			    item->string);
 		range_part = xstrndup(item->string, name_part - item->string);
 		name_part++;

t/t4211-line-log.sh

@@ -54,14 +54,14 @@ canned_test "-L 4:a.c -L 8,12:a.c simple" multiple-superset
 canned_test "-L 8,12:a.c -L 4:a.c simple" multiple-superset
 
 test_bad_opts "-L" "switch.*requires a value"
-test_bad_opts "-L b.c" "argument.*not of the form"
-test_bad_opts "-L 1:" "argument.*not of the form"
+test_bad_opts "-L b.c" "argument not .start,end:file"
+test_bad_opts "-L 1:" "argument not .start,end:file"
 test_bad_opts "-L 1:nonexistent" "There is no path"
 test_bad_opts "-L 1:simple" "There is no path"
-test_bad_opts "-L '/foo:b.c'" "argument.*not of the form"
+test_bad_opts "-L '/foo:b.c'" "argument not .start,end:file"
 test_bad_opts "-L 1000:b.c" "has only.*lines"
 test_bad_opts "-L 1,1000:b.c" "has only.*lines"
-test_bad_opts "-L :b.c" "argument.*not of the form"
+test_bad_opts "-L :b.c" "argument not .start,end:file"
 test_bad_opts "-L :foo:b.c" "no match"
 
 test_expect_success '-L X (X == nlines)' '